1. Field of the Invention
The present invention relates to a photoelectric converting device mounting apparatus for use with a camera or the like that mounts a photoelectric converting device such as a CCD and a fabrication method thereof.
2. Description of the Related Art
Cameras having a CCD have been widely used in various fields from home use to industrial use. Small medical cameras have been used for endoscopes. At present time, the minimum diameter of these cameras is 8 mm. However, since small diameters of cameras are being strongly desired to improve the characteristics of the endoscopes and marketability thereof, these very small cameras are being intensively studied and developed. The central portions of such cameras are CCDs. The packaging techniques for the CCDs are the most important development theme. As the CCD packages for conventional cameras, ceramic packages have been widely used from viewpoints of mass production and low cost. However, since the sizes of the ceramic packages are limited with the ceramic packages, alternate mounting techniques are being developed by many manufacturers.
Next, a related art reference of a conventional mounting method that is practically used will be described.
FIG. 23 shows an example of COG (Chip On Glass) method. In this method, an optical glass 1 is prepared (at step a). A thick gold film wiring layer 4 is formed at a plane portion 2 and an edge portion 3 of the optical glass (at step b). A low melting point metal paste is printed at a connecting portion for the CCD. An example of the metal paste is an alloy of indium and lead. The metal paste is heated and melted so as to form bumps 5 (at step c). A CCD 6 is prepared (at step d). Metal ball bumps 7 are formed on the CCD 6 according to wire bonding method (at step e). The metal bumps 5 on the optical glass 1 and the metal ball bumps 7 on the CCD 6 are heat pressed at a heat resisting temperature of the CCD or less (namely, 150.degree. C. or less) so as to connect the metal bumps 5 and the corresponding gold ball bumps 7 (at step f). In addition, to improve the mechanical strength of the connected portion, the space between the bump connected portions and the CCD pixels is filled and sealed with a resin 8 (at step g). Thereafter, an outer connecting electrode 9 disposed at an edge of the optical glass 1 is connected to a flexible substrate 10 (at step h). At this point, with an adhesive sheet or the like having for example anisotropy characteristics, the outer connecting electrode 9 and the flexible substrate 10 are heat pressed. As an advantage of the COG method, the alignment accuracy between the CCD and the optical glass is as high as 10 .mu.m.
Next, another related art reference will be described with reference to FIG. 24.
FIG. 24 are a schematic diagram showing SP-TAB (Single Point TAB) method. A TAB tape 17 that has metal plated bumps is prepared (at step a). The bumps of the TAB tape 17 are connected to corresponding electrode pads of a CCD 15 by a small bonding heater tool 8 according to ultrasonic heat pressing method (at step b). As with the COG method, the heat pressing is performed at the heat resisting temperature of the CCD or less (namely, 150.degree. C. or less) by the small heater tool 18. As the most advantage of this mounting method, after the CCD was mounted, the characteristics thereof can be inspected on the TAB tape 17. An optical adhesive agent 19 is coated on the upper surface of the CCD 15 (at step c). The optical glass 11 is precisely placed on the upper surface of the CCD 15 (at step d). At this point, the accuracy of the disposition is around .+-.20 .mu.m. The TAB tape 17 is bent from the outside of the CCD connected portion (at step e). Thus, the outer connecting leads can be easily extracted from the rear surface of the CCD.
However, the above-described related art references have the following drawbacks.
In the COG method, when the wiring layer is extracted from an edge of the optical glass 1, the screen printing is required. However, printing defects tend to take place at the edge portion, thereby lowering the yield of the fabrication. In addition, after the CCD package was mounted, a step for connecting an outer connecting flexible substrate is required. Thus, the fabrication process is complicated. On the other hand, in the SP-TAB method, it is difficult to precisely adhere the optical glass 11 and the adhesive agent 19. As shown in FIG. 25, the optical glass 11 should be placed on the upper portion of the TAB leads 17 disposed on both edges of the CCD. Such a construction is technically difficult to accomplish. In addition, the TAB leads should be connected to the corresponding pins of the electrode portions of the CCD according to the heat pressing method. Thus, this method takes a long time and thereby ineffective. As a drawback in common with the COG method and the SP-TAB method, a cavity takes place in the CCD image area. In other words, after the package was mounted, it is filled and sealed with a resin. However, the gap between the CCD and the optical glass other than the connecting portions of the electrode pads is relatively large (from 20 to 50 .mu.m). Thus, when the package is filled and sealed with the resin, the resin enters the CCD image area. Thus, the effect of focusing macro lenses is optically lost, thereby deteriorating the characteristics of the CCD.